Flew 18 km² of low-altitude magnetics at 60 m AGL over alluvium in western Nevada last week, and the NE-trending mag high lines up with a 250 ppm Cu and 20 ppm Mo soil corridor plus skarn float with calc-silicate and magnetite; I’m leaning toward a porphyry-related system. Before drilling, would you prioritize gradient IP to map chargeability/resistivity or cut a few trenches to ground-truth alteration and structure?
I’d go gradient IP first under that western NV alluvium — trenches rarely hit competent bedrock, and chargeability will vector along that 250 ppm Cu/20 ppm Mo corridor. > magnetite; I’m leaning toward a porphyry-related system. Before drilling, would you prioritize gradient IP to map chargeability/resistivity Agree — run a few tightly spaced gradient lines across the NE trend, then infill with dipole–dipole if a chargeability spine shows. Only trench where skarn float clusters on thin colluvium, and budget a water truck for contact in dry gravel.
Given that ‘NE-trending mag high’ under western NV alluvium, I’d shoot a couple CSAMT lines perpendicular to the 250 ppm Cu/20 ppm Mo corridor — faster and cheaper for me than deep trenches that stall in gravel. On a similar job, CSAMT plus a few 1–2 m backhoe test pits on skarn float clusters mapped the feeder; if you do run IP, pole–dipole with longer dipoles handled the cover better than tight dipole–dipole. Solid background here: https://pubs.usgs.gov/sir/2010/5070/A/.